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To evaluate the functional activity of thrombocytes in older patients with NSTE-ACS, including its dependence on frailty and comorbidity.
43 patients with NSTE-ACS were included into the study. All patients went through the standard therapy, including dual antiplatelet. The number of GPIIb-IIIa receptors (according to the MFI - average fluorescence intensity) and P-selectin expression on the platelet surface before and after activation of 10 μm ADP were assessed by flow cytometry using fluorescently labeled monoclonal antibodies CD61-FITC and CD62P-PE on Flow cytometer CYTOMICS FC 500. The comorbidity was assessed by the Charlson index. The index of frailty was calculated with the questionnaire by M. Hoover et al. Control groups included: healthy individuals (23 people); patients with stable cardiovascular diseases (42 patients).
In older patients with NSTE-ACS, the number of GPIIb-IIIa receptors as before activation was significantly higher than in patients under 60 years old (7.46 (6.46, 8.79) MFI vs 5.91 (4.58; 6, 29) MFI, p = 0.002) as after activation of ADP (12.5 (9.88; 14.5) MFI vs 6.34 (5.3, 6.84) MFI, p = 0.001). An increase in number of GPIIb-IIIa receptors after activation in older patients more than 50% indicates a cytoskeletal conversion of platelets and activation of platelet membrane receptors. Similar changes were observed while evaluating P-selectin expression on the surface of platelets: the indices in 60-year-old patients and the older ones significantly exceeded the indices in younger patients (0.69 (0.29, 1.05)% vs 0.35 (0.09; 0.40), p = 0.02), as well as the data obtained after induction (10.47 (2.93, 18.28)% vs 0.96 (0.63, 1.51)%, p = 0.001), which indicates hyperfunction of platelets in older patients. Initially, P-selectin expression was 0.53 (0.28, 1.00)% NSTE-ACS, which exceeded the values when compared with the control groups (p<0.00001), after ADP induction, P-selectin expression on the platelet surface was different in the focus groups (p<0,00001). When analyzing the functional activity of platelets in dependence on frailty, a more significant increase in the number of GPIIb-IIIa after ADP exposure was found in patients with frailty (11.7 (6.78, 15.0) than in the ones without frailty (6.57 (6.05, 6.99), p = 0.02) and similarly P-selectin (4.03 (1.09, 16.99) vs 1.51 (0.76, 2.23) respectively, p = 0.03). High comorbidity was also associated with excessive activation of platelet activity.
In older patients with NSTE-ACS, the functional activity of platelets and their activation in response to the inductor was significantly higher than in patients, younger 60 years old, which is probably associated with unfavorable outcomes in these patients, a greater risk of repeated myocardial infarctions. In the case of frailty, higher platelets aggregation was observed than with its absence.